Donald Trump drew a red line for Special Counsel Robert Mueller when it came to looking at Trump’s financial records. But if there’s a red line out there, Mueller doesn’t see it.

The former FBI director leading the probe into the Trump campaign’s possible ties to Russia is taking a page from the playbook federal prosecutors have used for decades in criminal investigations, from white-collar fraud to mob racketeering:

Follow the money. Start small and work up. See who will “flip” and testify against higher-ups by pursuing charges such as tax evasion, money laundering, conspiracy and obstruction of justice.

The finances of Donald Trump and those around him have become a critical part of the picture as the special counsel draws together his case. 

The Virginia home of former Trump campaign chairman Paul Manafort was subject to a pre-dawn, no-knock raid by FBI agents seeking information likely related to the $12 million in under-the-table funds Manafort is accused of getting for his work for pro-Russian factors in Ukraine, or the mysterious set of collateral-free loans that have allowed him to add two more homes to a portfolio that includes a condo in Trump Tower. Mueller has extended this push on Manafort by pulling in Manafort’s son-in-law, whose own finances are entangled in a series of real estate deals and off-shore accounts.

But it’s not just Manafort who has been a target of Mueller’s growing team of powerhouse lawyers and investigators. Donald Trump Jr. is reported to be a focus of the special counsel’s efforts, with particular attention to the circumstances surrounding the meeting that Trump Jr. hosted at Trump Tower in June of 2016, where the Trump campaign was offered material attacking Hillary Clinton by representatives of the Russian government.

And those are just the start.

Jay Sekulow, part of Trump’s legal team, denies that Mueller is putting together a racketeering case against Trump.

Sekulow also said it’s “fundamentally incorrect” to assume that Mueller is conducting a mob-style investigation when it comes to Trump and his family members, at least based on what he’s seen to date.

But Sekulow appears to have seen something quite different from everyone else.

"Mueller is no dummy," said William Mateja, a former federal prosecutor who investigated white-collar crime and served at the Justice Department when Mueller was director of the Federal Bureau of Investigation. "You use crimes like money laundering and tax evasion to get cooperation from people who might be in the know."

In addition to Manafort and Trump Jr., Mueller is known to be looking into the activities of Jared Kushner, including how his family has used connections to Trump to convince Chinese investors to buy into his properties.

One other person known to have been central to Mueller’s investigations is former national security adviser Michael Flynn. Flynn’s dealings with both Russia and Turkey certainly present plenty of potential wrongdoing. However, those same issues make Flynn a figure who might be eager to flip and cooperate with special counsel.

In any case, as Mueller piles up evidence against Manafort, Trump Jr., Kushner, Flynn and others, it’s clear that none of them are at the top of this investigation.

Among the experienced prosecutors he’s recruited in that effort is Andrew Weissmann, who worked in the 1990s to dismantle crime families on racketeering charges. He squeezed lower-level mobsters to become cooperating witnesses, a tactic that eventually led to the conviction of Genovese crime boss Vincent "The Chin" Gigante for racketeering in 1997. 

In this case, they’re not going after “the Chin” it’s more, “the Hair.”